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Discovery of single material that produces white light could boost efficiency, appeal of LED bulbs

By Christine Billau : December 5th, 2018

Physicists at The University of Toledo are part of an international team of scientists who discovered a single material that produces white light, opening the door for a new frontier in lighting, which accounts for one-fifth of global energy consumption.

“Due to its high efficiency, this new material can potentially replace the current phosphors used in LED lights — eliminating the blue-tinged hue — and save energy,” said Dr. Yanfa Yan, UT professor of physics. “More research needs to be done before it can be applied to consumer products, but the ability to reduce the power that bulbs consume and improve the color quality of light that the bulbs emit is a positive step to making the future more environmentally friendly.”

Dr. Xiaoming Wang, left, and Dr. Yanfa Yan are part of an international team that discovered a single material that produces white light.

The renewable energy research was recently published in Nature, the world’s leading multidisciplinary science journal.

The equation to make the inorganic compound combines a lead-free double perovskite with sodium.

“Together, cesium, silver, indium and chloride emit white light, but the efficiency is very low and not usable,” Yan said. “When you incorporate sodium, the efficiency increases dramatically. However, when sodium concentration reaches beyond 40 percent, side effects occur and the white light emission efficiency starts to drop below the peak of 86 percent.”

Supported by the U.S. Department of Energy’s Energy Frontier Research Center in Colorado known as CHOISE, Yan and Dr. Xiaoming Wang, UT postdoctoral researcher, conducted the theoretical calculations that revealed why the new material created through experiments by a team led by Dr. Jiang Tang at Huazhong University of Science and Technology in China produces high-efficiency white light.

“It was a wonderful experience working with Dr. Wang and Dr. Yan. Their professional theoretical simulation helps to reveal the emission mechanism of this miracle material,” said Tang, professor at Huazhong University of Science and Technology’s Wuhan National Laboratory. “This lead-free all-inorganic perovskite not only emits stable and efficient warm-white light that finds itself useful for solid-state lighting, but also shows as an encouraging example that lead-free perovskites could even show better performance than their lead cousins.”

“Their work is truly impressive,” Dr. Sanjay Khare, professor and chair of the UT Department of Physics and Astronomy, said. “Emission of white light from a single material is likely to open a whole new field in opto-electronics.”

Monash University, Jilin University, University of Toronto, Tsinghua University, Chinese Academy of Sciences and Wuhan University also contributed to the research.